RoseKavalier is the main popularizer of Metataker; without him, the number of people who completed this map would be much smaller because they wouldn't be able to.
This is very interesting. Did Rosekavalier complete the map himself without spoilers?
Even if "such a pro" Dandy (I can't help but laugh at his words about his qualifications and his assessment of others' qualifications, sorry) directly said that he wouldn't be able to complete many battles (like Fantomas) on his own.
Added 5 minutes later
What's even more interesting is not this. In my opinion, creating such battles is much more difficult than completing them. What was going on in Biobob's mind when he came up with that battle against 160 creatures, which I think is probably the most twisted in Metataker.